[U-Boot] arm, da850: Question about gpio control

[Gabriele Filosofi]

Hi all,

In board/davinci/da8xxevm/da850.c

#ifdef CONFIG_USE_NOR
                /* Set the GPIO direction as output */
                clrbits_be32((u32 *)GPIO_BANK0_REG_DIR_ADDR, (0x01 << 11));

                /* Set the output as low */
                val = readl(GPIO_BANK0_REG_SET_ADDR);
                val |= (0x01 << 11);
                writel(val, GPIO_BANK0_REG_CLR_ADDR);
#endif


It works, however is it the right way to put a gpio low ?
Why do we need to read the SET register, change its content, and write the CLR register ?


A second question is also related to GPIO control from within board_init.
I can toggle GP2[6] high or low using the code above, but I cannot do the same for GP2[12]. Why ?


After having done the following, the pin 25 of J30 still remain to logic level 1 !

int mycode(void)
{
                const struct pinmux_config gpio_pins[] = {
                               { pinmux(5), 8, 3 },
                };

                u32 val;

                /* PinMux for GPIO */
                if (davinci_configure_pin_mux(gpio_pins, ARRAY_SIZE(gpio_pins)) != 0)
                               return 1;

                /* Set the GPIO direction as output */
                clrbits_be32((u32 *)GPIO_BANK2_REG_DIR_ADDR, (0x01 << 12));

                /* Set the output as low */
                val = readl(GPIO_BANK2_REG_CLR_ADDR);
                val |= (0x01 << 12);
                writel(val, GPIO_BANK2_REG_CLR_ADDR);

                return 0;
}

Thanks,
Gabriele